Spin state modulation of iron spin crossover complexes via hydrogen-bonding self-assembly.

Iron complexes derived from 6-diaminotriazyl-2,2'-bipyridines display spin crossover behaviour, and hydrogen bonding-controlled self-assembly with a suitable barbiturate partner can modulate the crossover from mixed low and high spin to high spin. This system is the first to use solution-phase self-assembly of complementary hydrogen-bonding organic species to modulate spin state.